1. Technical Field
The present invention relates to an image processing device, an image display apparatus, and an image processing method.
2. Related Art
In recent years, high performance image display apparatuses such as large screen televisions or projectors have been spread widely, and in such image display apparatuses, improvement in image quality of the display images becomes further more important. In particular, regarding the projectors as image display apparatuses capable of enhancing freedom of installation owing to a lens shift function allowing alteration of positions of projection images on the screen without moving the housing, demands on further improvements in image quality have been increased due to an improvement of the image quality of contents themselves.
Regarding such projectors, JP-A-61-150487 discloses a projector using a transmissive matrix liquid crystal display device as a light valve. This projector is provided with a plurality of dichroic mirrors, separates a light beam from a light source into three light beams of primary colors of R, G, and B with the plurality of dichroic mirrors, transmits the light beams through respective liquid crystal display devices, and then projects the light beams on a screen via a projection lens. In this case, the transmitted light beams from the liquid crystal display devices are combined by an optical device such as a mirror in such a manner as to match the two-dimensional pixel arrangements with each other.
In this kind of projector, it is possible to achieve improvement in image quality of display images by increasing the number of pixels of the matrix liquid crystal display device, for example, and executing light modulation based on the image signal corresponding to the contents to execute image display.
However, if the number of pixels of a display image by the projector is increased, positioning of each pixel by an optical system tends to become more difficult. For example, a projection lens provided to the projector has chromatic aberration, and the refractive index thereof varies with the wavelength. Therefore, unprecedented accuracy is required for the aberration accuracy of the optical system provided to the projector. However, since projection conditions for the optical system are varied by shifting the projection lens, it is difficult to accurately adjust all of the display positions of sub-pixels constituting each pixel.
Although such misalignment of the display positions of the sub-pixels has been negligible with small number of display pixels, the misalignment of the display positions of the sub-pixels has become noticeable as the number of display pixels increases, and the misalignment of the display positions of the sub-pixels has come to incur degradation of image quality.